#include "EEPROM.h"
// See http://www.st.com/web/en/resource/technical/document/application_note/CD00165693.pdf

/**
  * @brief  Check page for blank
  * @param  page base address
  * @retval Success or error
  *     EEPROM_BAD_FLASH:   page not empty after erase
  *     EEPROM_OK:          page blank
  */
uint16_t EEPROMClass::EE_CheckPage(uint32_t pageBase, uint16_t status)
{
    uint32_t pageEnd = pageBase + (uint32_t)PageSize;

    // Page Status not EEPROM_ERASED and not a "state"
    if ((*(__IO uint16_t*)pageBase) != EEPROM_ERASED && (*(__IO uint16_t*)pageBase) != status)
        return EEPROM_BAD_FLASH;
    for(pageBase += 4; pageBase < pageEnd; pageBase += 4)
        if ((*(__IO uint32_t*)pageBase) != 0xFFFFFFFF)  // Verify if slot is empty
            return EEPROM_BAD_FLASH;
    return EEPROM_OK;
}

/**
  * @brief  Erase page with increment erase counter (page + 2)
  * @param  page base address
  * @retval Success or error
  *         FLASH_COMPLETE: success erase
  *         - Flash error code: on write Flash error
  */
FLASH_Status EEPROMClass::EE_ErasePage(uint32_t pageBase)
{
    FLASH_Status FlashStatus;
    uint16_t data = (*(__IO uint16_t*)(pageBase));
    if ((data == EEPROM_ERASED) || (data == EEPROM_VALID_PAGE) || (data == EEPROM_RECEIVE_DATA))
        data = (*(__IO uint16_t*)(pageBase + 2)) + 1;
    else
        data = 0;

    //FlashStatus = FLASH_ErasePage(pageBase);
    if (FlashStatus == FLASH_COMPLETE)
        FlashStatus = FLASH_ProgramHalfWord(pageBase + 2, data);

    return FlashStatus;
}

/**
  * @brief  Check page for blank and erase it
  * @param  page base address
  * @retval Success or error
  *         - Flash error code: on write Flash error
  *         - EEPROM_BAD_FLASH: page not empty after erase
  *         - EEPROM_OK:            page blank
  */
uint16_t EEPROMClass::EE_CheckErasePage(uint32_t pageBase, uint16_t status)
{
    uint16_t FlashStatus;
    if (EE_CheckPage(pageBase, status) != EEPROM_OK)
    {
        FlashStatus = EE_ErasePage(pageBase);
        if (FlashStatus != FLASH_COMPLETE)
            return FlashStatus;
        return EE_CheckPage(pageBase, status);
    }
    return EEPROM_OK;
}

/**
  * @brief  Find valid Page for write or read operation
  * @param  Page0: Page0 base address
  *         Page1: Page1 base address
  * @retval Valid page address (PAGE0 or PAGE1) or NULL in case of no valid page was found
  */
uint32_t EEPROMClass::EE_FindValidPage(void)
{
    uint16_t status0 = (*(__IO uint16_t*)PageBase0);        // Get Page0 actual status
    uint16_t status1 = (*(__IO uint16_t*)PageBase1);        // Get Page1 actual status

    if (status0 == EEPROM_VALID_PAGE && status1 == EEPROM_ERASED)
        return PageBase0;
    if (status1 == EEPROM_VALID_PAGE && status0 == EEPROM_ERASED)
        return PageBase1;

    return 0;
}

/**
  * @brief  Calculate unique variables in EEPROM
  * @param  start: address of first slot to check (page + 4)
  * @param  end: page end address
  * @param  address: 16 bit virtual address of the variable to excluse (or 0XFFFF)
  * @retval count of variables
  */
uint16_t EEPROMClass::EE_GetVariablesCount(uint32_t pageBase, uint16_t skipAddress)
{
    uint16_t varAddress, nextAddress;
    uint32_t idx;
    uint32_t pageEnd = pageBase + (uint32_t)PageSize;
    uint16_t count = 0;

    for (pageBase += 6; pageBase < pageEnd; pageBase += 4)
    {
        varAddress = (*(__IO uint16_t*)pageBase);
        if (varAddress == 0xFFFF || varAddress == skipAddress)
            continue;

        count++;
        for(idx = pageBase + 4; idx < pageEnd; idx += 4)
        {
            nextAddress = (*(__IO uint16_t*)idx);
            if (nextAddress == varAddress)
            {
                count--;
                break;
            }
        }
    }
    return count;
}

/**
  * @brief  Transfers last updated variables data from the full Page to an empty one.
  * @param  newPage: new page base address
  * @param  oldPage: old page base address
  * @param  SkipAddress: 16 bit virtual address of the variable (or 0xFFFF)
  * @retval Success or error status:
  *           - FLASH_COMPLETE: on success
  *           - EEPROM_OUT_SIZE: if valid new page is full
  *           - Flash error code: on write Flash error
  */
uint16_t EEPROMClass::EE_PageTransfer(uint32_t newPage, uint32_t oldPage, uint16_t SkipAddress)
{
    uint32_t oldEnd, newEnd;
    uint32_t oldIdx, newIdx, idx;
    uint16_t address, data, found;
    FLASH_Status FlashStatus;

    // Transfer process: transfer variables from old to the new active page
    newEnd = newPage + ((uint32_t)PageSize);

    // Find first free element in new page
    for (newIdx = newPage + 4; newIdx < newEnd; newIdx += 4)
        if ((*(__IO uint32_t*)newIdx) == 0xFFFFFFFF)    // Verify if element
            break;                                  //  contents are 0xFFFFFFFF
    if (newIdx >= newEnd)
        return EEPROM_OUT_SIZE;

    oldEnd = oldPage + 4;
    oldIdx = oldPage + (uint32_t)(PageSize - 2);

    for (; oldIdx > oldEnd; oldIdx -= 4)
    {
        address = *(__IO uint16_t*)oldIdx;
        if (address == 0xFFFF || address == SkipAddress)
            continue;                       // it's means that power off after write data

        found = 0;
        for (idx = newPage + 6; idx < newIdx; idx += 4)
            if ((*(__IO uint16_t*)(idx)) == address)
            {
                found = 1;
                break;
            }

        if (found)
            continue;

        if (newIdx < newEnd)
        {
            data = (*(__IO uint16_t*)(oldIdx - 2));

            FlashStatus = FLASH_ProgramHalfWord(newIdx, data);
            if (FlashStatus != FLASH_COMPLETE)
                return FlashStatus;

            FlashStatus = FLASH_ProgramHalfWord(newIdx + 2, address);
            if (FlashStatus != FLASH_COMPLETE)
                return FlashStatus;

            newIdx += 4;
        }
        else
            return EEPROM_OUT_SIZE;
    }

    // Erase the old Page: Set old Page status to EEPROM_EEPROM_ERASED status
    data = EE_CheckErasePage(oldPage, EEPROM_ERASED);
    if (data != EEPROM_OK)
        return data;

    // Set new Page status
    FlashStatus = FLASH_ProgramHalfWord(newPage, EEPROM_VALID_PAGE);
    if (FlashStatus != FLASH_COMPLETE)
        return FlashStatus;

    return EEPROM_OK;
}

/**
  * @brief  Verify if active page is full and Writes variable in EEPROM.
  * @param  Address: 16 bit virtual address of the variable
  * @param  Data: 16 bit data to be written as variable value
  * @retval Success or error status:
  *           - FLASH_COMPLETE: on success
  *           - EEPROM_PAGE_FULL: if valid page is full (need page transfer)
  *           - EEPROM_NO_VALID_PAGE: if no valid page was found
  *           - EEPROM_OUT_SIZE: if EEPROM size exceeded
  *           - Flash error code: on write Flash error
  */
uint16_t EEPROMClass::EE_VerifyPageFullWriteVariable(uint16_t Address, uint16_t Data)
{
    FLASH_Status FlashStatus;
    uint32_t idx, pageBase, pageEnd, newPage;
    uint16_t count;

    // Get valid Page for write operation
    pageBase = EE_FindValidPage();
    if (pageBase == 0)
        return  EEPROM_NO_VALID_PAGE;

    // Get the valid Page end Address
    pageEnd = pageBase + PageSize;          // Set end of page

    for (idx = pageEnd - 2; idx > pageBase; idx -= 4)
    {
        if ((*(__IO uint16_t*)idx) == Address)      // Find last value for address
        {
            count = (*(__IO uint16_t*)(idx - 2));   // Read last data
            if (count == Data)
                return EEPROM_OK;
            if (count == 0xFFFF)
            {
                FlashStatus = FLASH_ProgramHalfWord(idx - 2, Data); // Set variable data
                if (FlashStatus == FLASH_COMPLETE)
                    return EEPROM_OK;
            }
            break;
        }
    }

    // Check each active page address starting from begining
    for (idx = pageBase + 4; idx < pageEnd; idx += 4)
        if ((*(__IO uint32_t*)idx) == 0xFFFFFFFF)               // Verify if element
        {
            //  contents are 0xFFFFFFFF
            FlashStatus = FLASH_ProgramHalfWord(idx, Data); // Set variable data
            if (FlashStatus != FLASH_COMPLETE)
                return FlashStatus;
            FlashStatus = FLASH_ProgramHalfWord(idx + 2, Address);  // Set variable virtual address
            if (FlashStatus != FLASH_COMPLETE)
                return FlashStatus;
            return EEPROM_OK;
        }

    // Empty slot not found, need page transfer
    // Calculate unique variables in page
    count = EE_GetVariablesCount(pageBase, Address) + 1;
    if (count >= (PageSize / 4 - 1))
        return EEPROM_OUT_SIZE;

    if (pageBase == PageBase1)
        newPage = PageBase0;        // New page address where variable will be moved to
    else
        newPage = PageBase1;

    // Set the new Page status to RECEIVE_DATA status
    FlashStatus = FLASH_ProgramHalfWord(newPage, EEPROM_RECEIVE_DATA);
    if (FlashStatus != FLASH_COMPLETE)
        return FlashStatus;

    // Write the variable passed as parameter in the new active page
    FlashStatus = FLASH_ProgramHalfWord(newPage + 4, Data);
    if (FlashStatus != FLASH_COMPLETE)
        return FlashStatus;

    FlashStatus = FLASH_ProgramHalfWord(newPage + 6, Address);
    if (FlashStatus != FLASH_COMPLETE)
        return FlashStatus;

    return EE_PageTransfer(newPage, pageBase, Address);
}

EEPROMClass::EEPROMClass(void)
{
    PageBase0 = EEPROM_PAGE0_BASE;
    PageBase1 = EEPROM_PAGE1_BASE;
    PageSize = EEPROM_PAGE_SIZE;
    Status = EEPROM_NOT_INIT;
}

uint16_t EEPROMClass::init(uint32_t pageBase0, uint32_t pageBase1, uint32_t pageSize)
{
    PageBase0 = pageBase0;
    PageBase1 = pageBase1;
    PageSize = pageSize;
    return init();
}

uint16_t EEPROMClass::init(void)
{
    uint16_t status0, status1;
    FLASH_Status FlashStatus;

    FLASH_Unlock();
    Status = EEPROM_NO_VALID_PAGE;

    status0 = (*(__IO uint16_t *)PageBase0);
    status1 = (*(__IO uint16_t *)PageBase1);

    switch (status0)
    {
    /*
            Page0               Page1
            -----               -----
        EEPROM_ERASED       EEPROM_VALID_PAGE           Page1 valid, Page0 erased
                            EEPROM_RECEIVE_DATA         Page1 need set to valid, Page0 erased
                            EEPROM_ERASED               make EE_Format
                            any                         Error: EEPROM_NO_VALID_PAGE
    */
    case EEPROM_ERASED:
        if (status1 == EEPROM_VALID_PAGE)           // Page0 erased, Page1 valid
            Status = EE_CheckErasePage(PageBase0, EEPROM_ERASED);
        else if (status1 == EEPROM_RECEIVE_DATA)    // Page0 erased, Page1 receive
        {
            FlashStatus = FLASH_ProgramHalfWord(PageBase1, EEPROM_VALID_PAGE);
            if (FlashStatus != FLASH_COMPLETE)
                Status = FlashStatus;
            else
                Status = EE_CheckErasePage(PageBase0, EEPROM_ERASED);
        }
        else if (status1 == EEPROM_ERASED)          // Both in erased state so format EEPROM
            Status = format();
        break;
    /*
            Page0               Page1
            -----               -----
        EEPROM_RECEIVE_DATA EEPROM_VALID_PAGE           Transfer Page1 to Page0
                            EEPROM_ERASED               Page0 need set to valid, Page1 erased
                            any                         EEPROM_NO_VALID_PAGE
    */
    case EEPROM_RECEIVE_DATA:
        if (status1 == EEPROM_VALID_PAGE)           // Page0 receive, Page1 valid
            Status = EE_PageTransfer(PageBase0, PageBase1, 0xFFFF);
        else if (status1 == EEPROM_ERASED)          // Page0 receive, Page1 erased
        {
            Status = EE_CheckErasePage(PageBase1, EEPROM_ERASED);
            if (Status == EEPROM_OK)
            {
                FlashStatus = FLASH_ProgramHalfWord(PageBase0, EEPROM_VALID_PAGE);
                if (FlashStatus != FLASH_COMPLETE)
                    Status = FlashStatus;
                else
                    Status = EEPROM_OK;
            }
        }
        break;
    /*
            Page0               Page1
            -----               -----
        EEPROM_VALID_PAGE   EEPROM_VALID_PAGE           Error: EEPROM_NO_VALID_PAGE
                            EEPROM_RECEIVE_DATA         Transfer Page0 to Page1
                            any                         Page0 valid, Page1 erased
    */
    case EEPROM_VALID_PAGE:
        if (status1 == EEPROM_VALID_PAGE)           // Both pages valid
            Status = EEPROM_NO_VALID_PAGE;
        else if (status1 == EEPROM_RECEIVE_DATA)
            Status = EE_PageTransfer(PageBase1, PageBase0, 0xFFFF);
        else
            Status = EE_CheckErasePage(PageBase1, EEPROM_ERASED);
        break;
    /*
            Page0               Page1
            -----               -----
            any             EEPROM_VALID_PAGE           Page1 valid, Page0 erased
                            EEPROM_RECEIVE_DATA         Page1 valid, Page0 erased
                            any                         EEPROM_NO_VALID_PAGE
    */
    default:
        if (status1 == EEPROM_VALID_PAGE)
            Status = EE_CheckErasePage(PageBase0, EEPROM_ERASED);   // Check/Erase Page0
        else if (status1 == EEPROM_RECEIVE_DATA)
        {
            FlashStatus = FLASH_ProgramHalfWord(PageBase1, EEPROM_VALID_PAGE);
            if (FlashStatus != FLASH_COMPLETE)
                Status = FlashStatus;
            else
                Status = EE_CheckErasePage(PageBase0, EEPROM_ERASED);
        }
        break;
    }
    return Status;
}

/**
  * @brief  Erases PAGE0 and PAGE1 and writes EEPROM_VALID_PAGE / 0 header to PAGE0
  * @param  PAGE0 and PAGE1 base addresses
  * @retval Status of the last operation (Flash write or erase) done during EEPROM formating
  */
uint16_t EEPROMClass::format(void)
{
    uint16_t status;
    FLASH_Status FlashStatus;

    FLASH_Unlock();

    // Erase Page0
    status = EE_CheckErasePage(PageBase0, EEPROM_VALID_PAGE);
    if (status != EEPROM_OK)
        return status;
    if ((*(__IO uint16_t*)PageBase0) == EEPROM_ERASED)
    {
        // Set Page0 as valid page: Write VALID_PAGE at Page0 base address
        FlashStatus = FLASH_ProgramHalfWord(PageBase0, EEPROM_VALID_PAGE);
        if (FlashStatus != FLASH_COMPLETE)
            return FlashStatus;
    }
    // Erase Page1
    return EE_CheckErasePage(PageBase1, EEPROM_ERASED);
}

/**
  * @brief  Returns the erase counter for current page
  * @param  Data: Global variable contains the read variable value
  * @retval Success or error status:
  *         - EEPROM_OK: if erases counter return.
  *         - EEPROM_NO_VALID_PAGE: if no valid page was found.
  */
uint16_t EEPROMClass::erases(uint16_t *Erases)
{
    uint32_t pageBase;
    if (Status != EEPROM_OK)
        if (init() != EEPROM_OK)
            return Status;

    // Get active Page for read operation
    pageBase = EE_FindValidPage();
    if (pageBase == 0)
        return  EEPROM_NO_VALID_PAGE;

    *Erases = (*(__IO uint16_t*)pageBase + 2);
    return EEPROM_OK;
}

/**
  * @brief  Returns the last stored variable data, if found,
  *         which correspond to the passed virtual address
  * @param  Address: Variable virtual address
  * @retval Data for variable or EEPROM_DEFAULT_DATA, if any errors
  */
uint16_t EEPROMClass::read (uint16_t Address)
{
    uint16_t data;
    read(Address, &data);
    return data;
}

/**
  * @brief  Returns the last stored variable data, if found,
  *         which correspond to the passed virtual address
  * @param  Address: Variable virtual address
  * @param  Data: Pointer to data variable
  * @retval Success or error status:
  *           - EEPROM_OK: if variable was found
  *           - EEPROM_BAD_ADDRESS: if the variable was not found
  *           - EEPROM_NO_VALID_PAGE: if no valid page was found.
  */
uint16_t EEPROMClass::read(uint16_t Address, uint16_t *Data)
{
    uint32_t pageBase, pageEnd;

    // Set default data (empty EEPROM)
    *Data = EEPROM_DEFAULT_DATA;

    if (Status == EEPROM_NOT_INIT)
        if (init() != EEPROM_OK)
            return Status;

    // Get active Page for read operation
    pageBase = EE_FindValidPage();
    if (pageBase == 0)
        return  EEPROM_NO_VALID_PAGE;

    // Get the valid Page end Address
    pageEnd = pageBase + ((uint32_t)(PageSize - 2));

    // Check each active page address starting from end
    for (pageBase += 6; pageEnd >= pageBase; pageEnd -= 4)
        if ((*(__IO uint16_t*)pageEnd) == Address)      // Compare the read address with the virtual address
        {
            *Data = (*(__IO uint16_t*)(pageEnd - 2));       // Get content of Address-2 which is variable value
            return EEPROM_OK;
        }

    // Return ReadStatus value: (0: variable exist, 1: variable doesn't exist)
    return EEPROM_BAD_ADDRESS;
}

/**
  * @brief  Writes/upadtes variable data in EEPROM.
  * @param  VirtAddress: Variable virtual address
  * @param  Data: 16 bit data to be written
  * @retval Success or error status:
  *         - FLASH_COMPLETE: on success
  *         - EEPROM_BAD_ADDRESS: if address = 0xFFFF
  *         - EEPROM_PAGE_FULL: if valid page is full
  *         - EEPROM_NO_VALID_PAGE: if no valid page was found
  *         - EEPROM_OUT_SIZE: if no empty EEPROM variables
  *         - Flash error code: on write Flash error
  */
uint16_t EEPROMClass::write(uint16_t Address, uint16_t Data)
{
    if (Status == EEPROM_NOT_INIT)
        if (init() != EEPROM_OK)
            return Status;

    if (Address == 0xFFFF)
        return EEPROM_BAD_ADDRESS;

    // Write the variable virtual address and value in the EEPROM
    uint16_t status = EE_VerifyPageFullWriteVariable(Address, Data);
    return status;
}

/**
  * @brief  Writes/upadtes variable data in EEPROM.
            The value is written only if differs from the one already saved at the same address.
  * @param  VirtAddress: Variable virtual address
  * @param  Data: 16 bit data to be written
  * @retval Success or error status:
  *         - EEPROM_SAME_VALUE: If new Data matches existing EEPROM Data
  *         - FLASH_COMPLETE: on success
  *         - EEPROM_BAD_ADDRESS: if address = 0xFFFF
  *         - EEPROM_PAGE_FULL: if valid page is full
  *         - EEPROM_NO_VALID_PAGE: if no valid page was found
  *         - EEPROM_OUT_SIZE: if no empty EEPROM variables
  *         - Flash error code: on write Flash error
  */
uint16_t EEPROMClass::update(uint16_t Address, uint16_t Data)
{
    if (read(Address) == Data)
        return EEPROM_SAME_VALUE;
    else
        return write(Address, Data);
}

/**
  * @brief  Return number of variable
  * @retval Number of variables
  */
uint16_t EEPROMClass::count(uint16_t *Count)
{
    if (Status == EEPROM_NOT_INIT)
        if (init() != EEPROM_OK)
            return Status;

    // Get valid Page for write operation
    uint32_t pageBase = EE_FindValidPage();
    if (pageBase == 0)
        return EEPROM_NO_VALID_PAGE;    // No valid page, return max. numbers

    *Count = EE_GetVariablesCount(pageBase, 0xFFFF);
    return EEPROM_OK;
}

uint16_t EEPROMClass::maxcount(void)
{
    return ((PageSize / 4) - 1);
}

EEPROMClass EEPROM;
